From seductive "she-devil" to naive girl-next-door, the mystery over American Amanda Knox's true character is key to a sensational appeal trial in Italy that now faces a verdict on Monday.

From seductive "she-devil" to naive girl-next-door, the mystery over American Amanda Knox's true character is key to a sensational appeal trial in Italy that now faces a verdict on Monday.

With her fresh-faced good looks, the blue-eyed Knox seemed an unlikely suspect for the brutal murder of her housemate Meredith Kercher in 2007, but accusers say the 24-year-old's demure nature hides a "demonic" soul.

Prosecutors have depicted her as lascivious and slovenly -- a drug-using party goer who regularly brought strange men back to her room for sex and exasperated housemates by leaving vibrators and erotic underwear on display.

They say Kercher was murdered after refusing to take part in a drug-fuelled sex game with Knox, her then boyfriend Raffaele Sollecito and immigrant Rudy Guede. Kercher was found naked in a pool of blood with her throat slit. She was 21.

Knox's family have presented a completely different picture of a loving, sporty girl who spoke proudly to her mother of her friendship with Kercher.

A New York Times editorial in 2009 called her: "An Innocent Abroad".

During her appeal, Knox herself pleaded: "How is it possible that I could be capable of such violence? How could I commit evil against a friend of mine?"

Overnight, the case become a media sensation, a whodunnit starring "Foxy Knoxy" -- the nickname Knox herself used on the Internet-based social network MySpace, though she maintains it referred to her childhood football skills.

Her "Angel Face" -- the title of a book about the case -- hit front pages across the world and prompted an upswell of support in the United States.

The glaring media spotlight, combined with leaks to scoop-hungry tabloids during the investigation and stories about her racy past from former friends, prompted fears that the Seattle native may not have been given a fair trial.

The British Daily Mail newspaper quoted a guest at Knox's going away party saying that it was a scene of debauchery, "with drinks, drugs and bodies everywhere... Everyone just wanted to get drunk, get high and get laid."

Friends of Amanda Knox groups sprang up in her hometown and on the Internet, with messages of support deploring the "warped image" created in the press.

Speaking in her own defence during the trial, Knox said she was innocent and had lied to police at the start because she had been subjected to "a steady crescendo" of abuse during long periods of questioning without a lawyer.

Though she was convicted in 2009 and sentenced to 26 years in prison, Knox protested her innocence and her supporters slammed the Italian justice system and called vociferously for her release as the appeal got underway.

Behind bars, the University of Washington student has wiled away four years reading Dostoyevsky and Hemingway and praying, according to a member of the Italian parliament who has published a book based on numerous talks with Knox.

In the collection of interviews, Knox dreams of freedom and talks about her hopes of being an interpreter or a writer, her love for nature, her longing for motherhood as well as her interest in Buddhism and Christianity.

MP Rocco Girlanda said Knox was "serene" during his visits, but every so often "a melancholic shadow passes through those beautiful blue eyes."

As the appeal trial winds up, Knox has looked increasingly pale and strained. She was shaking the last time she appeared in court.

Her defence has fiercely ridiculed the portrayal of Knox as a dominatrix "Venus in Furs" or a femme fatale who preys on weaker men, like the fictional "Jessica Rabbit" in the cartoon film "Who Framed Roger Rabbit?"

But for Carlo Pacelli -- a lawyer representing Patrick Lumumba, the bar owner that Knox misleadingly identified as the killer in her first statement to police -- the question remains: "Who is Amanda Knox?"

"She has a two-faced soul. One side is angelic, good, compassionate, in some ways saintly, the other is like a she-devil, it is demonic, satanic, diabolical and wants to live out borderline extreme behaviour.